JP2009218767A - Video/audio signal seamless switching device and video/audio signal seamless switching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video/audio signal seamless switching device capable of further strictly detecting the error of the compressed video/audio signals of an MPEG2 TS signal form each received from a plurality of signal routes, accurately selecting base band video/audio signals for which normal video/audio signals without the error are decoded, and seamlessly switching them. <P>SOLUTION: On the basis of error information 15 indicating the detected result of the error during decoding and/or the error of the base band video/audio signals after decoding when each of the compressed video/audio signals received in respective first-Nth reception base stations 8 is decoded to the base band video/audio signals in respective first-Nth video/audio decoders 13, one of the base band video/audio signals 14 after the decoding from the first-Nth video/audio decoders 13 is selected and seamlessly switched in a video/audio signal seamless switching circuit 16 and outputted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video / audio signal seamless switching apparatus and a video / audio signal seamless switching method for seamlessly switching a system of compressed video / audio signals transmitted through a plurality of signal paths, and in particular, in a process of decoding and returning to a baseband signal. The present invention relates to a video / audio signal seamless switching device and a video / audio signal seamless switching method for seamlessly switching signal paths based on detection results of abnormalities and the presence / absence of abnormalities in baseband signals after decoding.

  As a conventional system configuration for seamlessly switching the signal system of compressed video and audio signals transmitted from a plurality of signal paths, there is a technique described in Japanese Patent Laid-Open No. 2002-084215, “Route Diversity Receiver”. . The system configuration in Patent Document 1 is conceptually shown in FIG. 5, and the signal system of the video / audio signal is set to any signal by the TS signal seamless switch 35 installed in the broadcasting center 12. Switching to the signal from the route. As shown in FIG. 5, the video / audio signal from the camera 2 mounted on the mobile relay vehicle 1 is compressed and encoded by a video / audio encoder (ENC) 3 into an MPEG2 TS (Transport Stream) signal format. , FPU transmitter (Field Pickup Unit: wireless relay transmission device) 4 transmits. The MPEG2 TS signal digitally modulated by the FPU transmitter 4 is transmitted from the omnidirectional antenna 5 to the air as a microwave or UHF wave signal.

  The radio waves transmitted in the air are received by the receiving antennas 7 of the first, second,..., Nth receiving base stations 8 via the mobile radio line 6, and each FPU receiver 9. Is transmitted from each receiving base station 8 to the broadcasting center 12 via a wireless fixed line 10 such as a microwave or an optical fixed line 11.

In the broadcasting center 12, the TS signal seamless switching unit 35 starts from the receiving base station 8 having no abnormality in the MPEG2 TS signal level among the data from the first, second,..., Nth receiving base stations 8. Are seamlessly switched and output to the video / audio decoder 13 so that the video / audio decoder 13 decodes the baseband signal and abnormally receives video and audio from the mobile relay vehicle 1. It is reproducible. The video / audio decoder 13 decodes the TS signals that are sequentially input into a baseband signal, so that the video signal is displayed on the monitor 17 and the audio signal is output from the speaker 18.
JP 2002-084215 A (page 3-4)

  However, in the conventional technique such as Patent Document 1, a compressed video / audio signal is received as a TS signal, a signal abnormality is detected at the level of the received TS signal, and a signal having no abnormality is detected. This is a method of selecting and switching, and there is a problem that the actual data in the payload of the received signal is strictly detected and the switching is not performed seamlessly based on the detection result.

  In other words, the reason why the signal abnormality cannot be strictly detected in the prior art is that the signal abnormality detection at the TS signal level is performed by detecting an error in error correction processing such as Reed-Solomon error correction. This is because, when an abnormality that exceeds the limit of the error correction method related to page load occurs in the TS signal, such as an abnormality in actual data, the abnormality cannot be detected.

  The present invention has been made in view of such circumstances, and it is possible to more accurately detect an error in a received signal, select a normal received signal without an error, and switch seamlessly. An object of the present invention is to provide a switching device and a video / audio signal seamless switching method.

  As a result, a first object of the present invention is to provide a video / audio signal seamless switching device and a video / audio signal seamless switching method capable of improving the reliability of a video / audio signal transmission system. By detecting the abnormality of the video / audio signal more strictly than in the case of the TS signal level, the video / audio signal after seamless switching is prevented from being disturbed such as block noise, and the video / audio signal transmission system The first object is to improve the reliability of the system.

  A second object of the present invention is to provide a video / audio signal seamless switching device and a video / audio signal seamless switching method capable of improving the transmission efficiency of video / audio signals. In general, in radio transmission such as microwaves, the higher the transmission rate, the stronger the directivity of the radio wave, the more easily the radio line is interrupted by the presence of a shield such as a building, and the frequency of occurrence of abnormalities in received signals. Get higher. The video / audio signal seamless switching device and the video / audio signal seamless switching method according to the present invention provide a signal from another receiving base station that receives the same signal even if a radio base line is disconnected at a certain receiving base station. By switching seamlessly, it is possible to compensate for an increase in the probability of wireless channel disconnection due to an increase in transmission rate. As a result, video and audio are transmitted at a transmission rate close to the limit of transmission speed that can be transmitted over the wireless channel. The second object is to enable transmission of signals.

  In order to solve the above-described problems, the video / audio signal seamless switching device and the video / audio signal seamless switching method according to the present invention employ the following characteristic configuration.

  (1) A video / audio signal that is selected from MPEG2 TS (Transport Stream) signal format compressed video / audio signals transmitted from a plurality of signal paths, seamlessly switched, decoded into a baseband video / audio signal, and output. A seamless switching device comprising a video / audio decoder for decoding the compressed video / audio signal from each of a plurality of signal paths corresponding to each of the signal paths, and an error in decoding and / or each of the video / audio decoders Alternatively, based on the detection result of the error in the decoded baseband video / audio signal, one of the plurality of decoded baseband video / audio signals is selected and seamlessly switched and output. Audio signal seamless switching device.

  According to the video / audio signal seamless switching device and the video / audio signal seamless switching method of the present invention, the following effects can be obtained.

  In other words, the detection of abnormalities in the video and audio signals from each receiving base station is performed after demodulating the baseband signal, so that the abnormal detection of the video and audio signals can be performed more strictly, and the normal video can be detected more reliably. Audio signals can be selected and switched seamlessly, and the transmission efficiency and reliability of video and audio signals as a transmission system can be improved.

  Error detection at the TS signal level as in the case of the prior art can only be used to detect anomalies in the received signal that is not correctable from the error correction circuit, but error detection based on the baseband signal after decoding is possible. In this case, the reason why it is possible to more reliably detect the abnormality of the received signal is that the signal of each layer constituting the baseband signal is in light of the contents of the MPEG 2 signal standard defined for each layer. In addition, it is because error detection can be performed strictly.

That is, as a baseband signal layer of MPEG2,
(1) Sequence layer (2) GOP (Group Of Pictures) layer (3) Picture layer (4) Slice layer (5) Macro layer (6) There are six layers, and each layer is provided for each layer. Headers can be checked, and by checking for the presence or absence of illegal data in each header, it is possible to more strictly determine whether or not there is an abnormality in the received signal.

  Preferred embodiments of a video / audio signal seamless switching device and a video / audio signal seamless switching method according to the present invention will be described below with reference to the accompanying drawings.

(Features of the present invention)
Prior to the description of the embodiments of the present invention, the features of the present invention will be first outlined. The present invention includes a plurality of decoder circuits or decoder devices for decoding compressed video and audio signals sent from a plurality of receiving base stations as a plurality of signal paths, corresponding to the respective decoder circuits. / In the decoder device, the decoded video / audio signal is output, and at the same time, sequence errors and frame errors in the compressed data, whether or not there is an abnormality in decoding, and whether or not there is an abnormality in the decoded baseband signal data Is output to the switching control logic. In the switching control logic, based on the information indicating the presence / absence of detection of abnormality from each decoder circuit / decoder device, the video / audio signal of the signal path outputting the normal baseband video / audio signal is selected, The selected baseband video / audio signal is output by seamlessly switching the switching circuit.

(Configuration example of embodiment of the present invention)
Next, a configuration example of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a system configuration diagram conceptually showing an example of a system configuration for seamlessly switching the signal system of compressed video and audio signals in the present invention.

  As shown in FIG. 1, the configuration of the embodiment of the present invention includes a camera 2, a video / audio encoder 3, an FPU transmitter 4, and an omnidirectionality that are video / audio signal compression / transmission sources mounted on a mobile relay vehicle 1. The antenna 5, and a plurality of first, second,..., Nth received compressed video and audio signal receiving bases, a receiving base station 8, and an FPU receiver built in each receiving base station 8. 9. Broadcast center 12 which is a center base where compressed video and audio signals from a plurality of receiving base stations 8 are collected via a wireless fixed line 10 or an optical fixed line 11, and video / audio signal decoding switching installed in the broadcast center 12. A video / audio signal seamless switching device 20 which is a device, and a monitor, a LCD, a CRT, etc. for monitoring a baseband video / audio signal output from the video / audio signal seamless switching device 20 Motor 17, configured to include at least a speaker 18. The video / audio signal seamless switching device 20 includes a video / audio decoder 13, which is a plurality of video / audio signal decoding circuits (decoder circuits or decoder devices) prepared from the first, second,. / Contains at least a video / audio signal seamless switching circuit 16 for seamlessly selecting and outputting one of the outputs of the audio decoder 13.

  That is, the system configuration in FIG. 1 is different from that in FIG. 5 described above as the prior art. In the broadcast center 12, the video / audio signal seamless switching device 20 that forms a device unique to the present invention is provided as the first, second, .., A plurality of first, second,..., Nth video / audio decoders 13 are prepared in order to decode each received signal from the Nth plurality of receiving base stations 8 into a baseband video / audio signal. And a video / audio signal seamless switching circuit 16 for selecting and seamlessly switching any one of the decoded baseband video / audio signals output from the first, second,..., Nth video / audio decoders 13. Is provided.

(Description of operation of this system configuration)
Next, the operation of each component of the system configuration shown in FIG. 1 will be described. In FIG. 1, the operation of the video / audio signal compression / transmission source mounted on the mobile relay vehicle 1 is the same as in FIG. 5, and the video / audio signal from the camera 2 for shooting is a video / audio signal that is an MPEG2 encoder. The audio encoder (ENC) 3 compresses and encodes the signal into an MPEG2 TS (Transport Stream) signal format and transmits the signal to an FPU transmitter (Field Pickup Unit: wireless relay transmission device) 4. In the FPU transmitter 4 that generates the modulated radio transmission signal, the compression-encoded MPEG2 TS signal is digitally modulated into a radio transmission signal of microwave or UHF wave, and is emitted as a radio wave from the omnidirectional antenna 5 into the air. Is done.

  The radio waves emitted into the air are received by the receiving antennas 7 of the first, second,..., Nth receiving base stations 8 via the mobile radio link 6 as in the case of FIG. After being demodulated into digital data in the TS signal format by the respective FPU receivers 9, they are transmitted from each receiving base station 8 to the broadcasting center 12 via a wireless fixed line 10 such as a microwave or an optical fixed line 11. The

  Unlike the case of FIG. 5, the broadcast center 12 receives the TS data from the first, second,... Input to the corresponding first, second,..., Nth video / audio decoders 13. The first, second,..., Nth video / audio decoders 13 respectively convert the compressed video / audio signals in the TS signal format transmitted from the receiving base station 8 of the corresponding signal path into baseband video / audio signals. Are decoded and output as a video / audio signal 14, and when an abnormality is detected during decoding, or when there is an abnormality as a result of checking whether there is an error in each layer of the decoded baseband video / audio signal Information indicating that is output as error information 15. The video / audio signal 14 decoded into the baseband signal output from the video / audio decoder 13 and the error information 15 indicating the abnormality check result are output to the video / audio signal seamless switching circuit 16.

  In the video / audio signal seamless switching circuit 16, each video / audio decoded into a baseband signal transmitted from the first, second,..., Nth video / audio decoders 13 via a plurality of lines. An operation for seamlessly switching a signal system to be selected according to the content of the error information 15 while performing processing for matching the frame timing of the signal 14 and referring to the error information 15 output from each video / audio decoder 13 And a normal video / audio signal in which no error has occurred is selected and output from the video / audio signals 14 from the respective video / audio decoders 13. The video signal output from the video / audio signal seamless switching circuit 16 is displayed on the monitor 17, and the audio signal is output from the speaker 18.

  As shown in FIG. 2, each of the first, second,..., Nth video / audio decoders 13 includes the illegal MPEG data in the headers of the six layers of the decoded MPEG2 baseband signal. Check blocks for checking presence / absence are built in corresponding to each layer. That is, as shown below, six check blocks of a sequence layer check block 28, a GOP layer check block 29, a picture layer check block 30, a slice layer check block 31, a macro layer check block 32, and a block layer check block 33 However, it is built in corresponding to each layer, and an abnormality in each layer can be detected.

(1) Sequence layer check block 28: Check block for header for sequence layer (2) GOP layer check block 29: Check block for header for GOP (Group Of Pictures) layer (3) Picture layer check block 30: Picture layer (4) Slice layer check block 31: Slice layer header check block (5) Macro layer check block 32: Macro layer header check block (6) Block layer check block 33: Block Check block for header for layer

  2 is a block configuration diagram showing an example of the configuration of the check block for each layer of the baseband video / audio signal built in the video / audio decoder 13 shown in FIG. As shown in FIG. 2, the check results of the check blocks of each layer are collected in the error collecting circuit 34, and when an abnormality is detected in any layer, error information 15 indicating the abnormality detection is output. To do.

  FIG. 3 shows an example of the block configuration of the video / audio signal seamless switching device 20 shown in FIG. As shown in FIG. 3, the video / audio signal seamless switching device 20 decodes each compressed video / audio signal 19 transmitted from each of the first, second,..., Nth receiving base stations into a baseband signal. A plurality of (N) video / audio decoders 13 and a video / audio signal seamless switching circuit 16 for selecting and outputting the outputs of the plurality of video / audio decoders 13 in a seamless manner. .

  In FIG. 3, each video / audio decoder 13 outputs the baseband video / audio signal 14 after decoding as described above, and at the same time, the decoding error, the sequence error in the compressed data, the frame error, When an MPEG2 signal standard violation or the like in the header is detected, error information 15 is output. Here, each video / audio decoder 13 may be a decoder circuit (decoder chip) having a chip configuration or a decoder device having a device configuration.

  Further, as shown in FIG. 3, the video / audio signal seamless switching circuit 16 adjusts the phase of each of the video / audio signals 14 from the plurality of video / audio decoders 13 (matching the frame timing of each of the video / audio signals 14). Video / audio signals 14 from a plurality (N) of video / audio decoders 13 based on error information 15 from a plurality of delay adjustment circuits 21 and a plurality of video / audio decoders 13. Among them, a switching control logic 22 and a switching control logic 22 for selecting a video / audio signal 14 to be output from the video / audio signal seamless switching circuit 16 and outputting a control signal for seamless switching to the signal system of the selected video / audio signal 14. The signal system is switched based on the control signal from the selected video / audio. And a switching circuit 23 for outputting a video and audio signal 14 from Iodekoda 13.

  In the video / audio signal seamless switching device 20 shown in FIG. 3, the abnormality of the compressed video / audio signal 19 from each receiving base station 8 is detected after being demodulated into a baseband signal by the video / audio decoder 13. Therefore, the abnormal detection of the decoded video / audio signal 14 can be performed more strictly, and the video / audio signal seamless switching circuit 16 can select the normal video / audio signal free from errors more securely and switch it seamlessly. Therefore, it is possible to improve the transmission efficiency and reliability of video and audio signals as a transmission system.

(Configuration example of another embodiment of the present invention)
FIG. 4 is a system configuration diagram conceptually showing an example different from the above-described FIG. 1 of the system configuration for seamlessly switching the signal system of the compressed video / audio signal in the present invention. 4, the configuration of the first, second,..., Nth receiving base station 26 and the receiving antennas 24, 25 provided in each receiving base station 26 is the same as the system configuration of FIG. The different components are shown. The other components are the same as those in FIG. 1 and are given the same reference numerals as those in FIG.

  In the system configuration shown in FIG. 4, each of the first, second,..., Nth reception base stations 26 has the first, second,. The receiving base station 26 includes a plurality of receiving antennas (two first and second receiving antennas 24 and 25 in the case of the example of FIG. 4) and receives any one of the plurality of receiving antennas. A reception antenna switching circuit 27 that selects and receives a reception signal from the antenna is incorporated.

  Here, in the case of FIG. 4, the two first and second receiving antennas 24 and 25 may be configured as space diversity antennas having different spatial installation locations, horizontal installation, vertical installation, and the like. It may be configured as a space diversity antenna with different installation angles, or may be configured as another type of diversity antenna. The receiving antenna switching circuit 27 in each receiving base station 26 performs switching control so as to capture the radio signal of the receiving antenna with the higher receiving level of the two first and second receiving antennas 24 and 25. .

  That is, in the present embodiment, when the signal path is a wireless line that propagates in the air as radio waves, a plurality of antennas are used as reception antennas for receiving radio waves, and the reception level of each reception antenna is received. An example is shown in which control is performed so as to switch to a reception signal of a reception antenna having the highest level.

  In the present embodiment, in addition to the seamless switching operation by the video / audio signal seamless switching device 20 in the broadcast center 12 in the above-described embodiment, it is possible to improve the radio wave reception sensitivity in the receiving base station 8. In addition, seamless switching operations can be performed more reliably, and the transmission efficiency and reliability of video / audio signals as a transmission system can be further improved.

  The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention. For example, the embodiment of the present invention can be expressed as the following configuration in addition to the configuration (1) in the means for solving the problems.

(2) When detecting an error in the decoded baseband video / audio signal in each of the video / audio decoders, at least for each layer of the decoded baseband video / audio signal, a signal standard for each layer of MPEG2 is set. The video / audio signal seamless switching device according to (1), wherein the video / audio signal seamless switching device for checking whether or not the above is satisfied.
(3) The video / audio signal seamless switching device according to (1) or (2), further comprising delay adjusting means for aligning the phases of the decoded baseband video / audio signals from the plurality of video / audio decoders.
(4) A video / audio signal that is selected from MPEG2 TS (Transport Stream) signal format compressed video / audio signals transmitted from a plurality of signal paths, seamlessly switched, decoded into a baseband video / audio signal, and output. A seamless switching method, comprising: a video / audio decoder for decoding the compressed video / audio signal from each of a plurality of signal paths, corresponding to each of the signal paths, and a decoding error in each of the video / audio decoders and / or Alternatively, based on the detection result of the error in the decoded baseband video / audio signal, one of the plurality of decoded baseband video / audio signals is selected and seamlessly switched and output. Audio signal seamless switching method.
(5) When detecting an error in the baseband video / audio signal after decoding in each of the video / audio decoders, at least for each layer of the baseband video / audio signal after decoding, a signal standard for each layer of MPEG2 is set. (4) The video / audio signal seamless switching method of (4) for checking whether or not the above is satisfied.
(6) The video / audio signal seamless switching method according to (4) or (5), wherein the phases of the decoded baseband video / audio signals from the plurality of video / audio decoders are output with the phases aligned.
(7) When a plurality of signal paths of the compressed video and audio signals in the MPEG2 TS signal format are wireless lines that propagate as radio waves in the air, a plurality of antennas are used as receiving antennas for receiving the radio waves. The video / audio signal seamless switching method according to any one of (4) to (6), wherein a reception signal of a reception antenna having the highest reception level among the reception antennas is switched and received.

1 is a system configuration diagram conceptually showing an example of a system configuration for seamlessly switching a signal system of a compressed video / audio signal in the present invention. FIG. 2 is a block configuration diagram showing an example of a configuration of a check block for each layer of a baseband video / audio signal built in the video / audio decoder shown in FIG. 1. It is a block block diagram which shows an example of the block configuration of the video / audio signal seamless switching apparatus shown in FIG. FIG. 2 is a system configuration diagram conceptually showing an example different from FIG. 1 of the system configuration for seamlessly switching the signal system of the compressed video / audio signal in the present invention. It is a system configuration | structure figure which shows the system configuration | structure which switches the signal system | strain of the conventional compressed video / audio signal seamlessly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile relay vehicle 2 Camera 3 Video / audio encoder 4 FPU transmitter 5 Omnidirectional antenna 6 Mobile radio link 7 Reception antenna 8 Receiving base station 9 FPU receiver 10 Wireless fixed line 11 Optical fixed line 12 Broadcast center 13 Video / audio Decoder 14 Video / audio signal 15 Error information 16 Video / audio signal seamless switching circuit 17 Monitor 18 Speaker 19 Compressed video / audio signal 20 Video / audio signal seamless switching device 21 Delay adjustment circuit 22 Switching control logic 23 Switching circuit 24 First receiving antenna 25 2 receiving antennas 26 receiving base station 27 receiving antenna switching circuit 28 sequence layer check block 29 GOP layer check block 30 picture layer check block 31 slice layer check block 32 macro layer check block Click 33 Block Layer check block 34 error collecting circuit 35 TS signal seamlessly switch

Claims (7)

  A video / audio signal seamless switching device for selecting any one of MPEG2 TS (Transport Stream) signal format compressed video / audio signals transmitted from a plurality of signal paths, seamlessly switching them, and decoding and outputting them to baseband video / audio signals. A video / audio decoder for decoding the compressed video / audio signal from each of a plurality of signal paths is provided corresponding to each of the signal paths, and an error during decoding and / or after decoding in each of the video / audio decoders Based on the error detection result of the baseband video / audio signal, one of the decoded baseband video / audio signals is selected and seamlessly switched and output. Video / audio signal seamless switching device.   Whether at least each layer of the decoded baseband video / audio signal satisfies the signal standard for each layer of MPEG2 when detecting an error of the decoded baseband video / audio signal in each of the video / audio decoders The video / audio signal seamless switching device according to claim 1, wherein the video / audio signal seamless switching device is checked.   3. The video / audio signal seamless switching device according to claim 1, further comprising delay adjusting means for aligning the phases of the decoded baseband video / audio signals from the plurality of video / audio decoders. .   A video / audio signal seamless switching method of selecting any one of MPEG2 TS (Transport Stream) signal format compressed video / audio signals transmitted from a plurality of signal paths, seamlessly switching them, and decoding and outputting them to baseband video / audio signals A video / audio decoder for decoding the compressed video / audio signal from each of a plurality of signal paths is provided corresponding to each of the signal paths, and an error during decoding and / or after decoding in each of the video / audio decoders Based on the error detection result of the baseband video / audio signal, one of the decoded baseband video / audio signals is selected and seamlessly switched and output. To switch video and audio signals seamlessly.   Whether at least each layer of the decoded baseband video / audio signal satisfies the signal standard for each layer of MPEG2 when detecting an error of the decoded baseband video / audio signal in each of the video / audio decoders 5. The video / audio signal seamless switching method according to claim 4, further comprising checking whether or not.   6. The video / audio signal seamless switching method according to claim 4 or 5, wherein the phases of the decoded baseband video / audio signals from the plurality of video / audio decoders are output with the same phases.   When a plurality of signal paths of the compressed video and audio signals in the MPEG2 TS signal format are wireless lines that propagate as radio waves in the air, a plurality of antennas are used as receiving antennas for receiving the radio waves, and each of the receiving antennas 7. The video / audio signal seamless switching method according to claim 4, wherein the reception signal is switched to the reception signal of the reception antenna having the highest reception level.

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